NWS Forecast Discussion
868
FXUS61 KCTP 010315
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
1115 PM EDT Sat May 31 2025
.SYNOPSIS...
* Winds will begin diminishing tonight as clouds begin
scattering out and lifting.
* Dry conditions prevail for the first half of the week before
a return to showers and thunderstorms mid-to-late next week.
* Temperatures well-below average today trend warmer into next
week.
&&
.NEAR TERM /UNTIL 8 AM SUNDAY MORNING/...
Gusty gradient winds will continue for the first part of
tonight. The gustiness should diminish overnight, but most
places will still have wind speeds in the 8-10KT range due to
wrap around winds on the back side of the surface low.
Showers and thunderstorms have mostly left central PA. A few
sprinkles could be seen over the next couple of hours, but for
the most part drying out will begin to occur. Colder air has
quickly been ushered in behind the cold front, bringing temps
down quickly from today`s highs. Clouds will break up for much
of the area (esp S of I-80) early tonight. Temps won`t get crazy
cold, despite our cool start to the night and 0C 8H isotherm
invading the N. Expect the wind to help a little, and low temps
will turn out near 40F in the Alleghenies and m40s in the Susq
valley.
&&
.SHORT TERM /8 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
After the cool start, the sun should work on the damp ground
and the cool pocket aloft will help stratocu to form and congest
over the nrn half+ of the CWA during the day Sunday. The srn
half will end up mostly sunny. There is a tiny chc for a --SHRA
over the nrn tier, but the dryness of the airmass should
evaporate any bigger droplets before they hit the ground. Maxes
may fall short of 60F N and probably get right to 70F in the
SE.
Winds are expected to become calm Monday as the surface low
fully departs up New England into eastern Canada and high
pressure builds into the region. Monday morning will be the
coldest of the week with the lows in the NW mountains
threatening to drop as low as the upper 30s. There could be a
few hours of patchy frost early Monday in those locations.
Temperatures will begin to warm back up Monday afternoon with
westerly flow, but still remain below seasonal averages for
this time of year. Dry conditions will continue through the
early part of this week.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Late evening update.
12Z GFS and EC not really close by 240 hrs. Either way, expect
some wet weather again after Wed, so enjoy Monday into
Wednesday, when we can have both some warm weather and dry
weather, which we really need after how wet it has been this
month of May. Some locations over 10 inches of rain for this
May.
The next cold front will be near the area still by next
weekend, so while the chance of showers may be lower by then
after higher POPS before that period, the front will not be
that far from the southern border of PA.
Earlier discussion below.
On the large-scale, the amplified, blocky upper-level pattern
we`ve seen now for several weeks is still forecast to flatten
out and progress next week, allowing significant height rises
aloft to develop over the eastern CONUS. This signals a trend
towards much warmer temperatures and generally less rainfall
than we`ve experienced lately.
As for the daily sensible weather, after a chilly start early
Monday, the first half of next week turns much warmer, with
rain-free conditions anticipated. Afternoon highs are expected
to surge well into the 80s by Tuesday and Wednesday, and could
even make a run at 90 across the Lower Susquehanna Valley.
A slow moving cold front could make a close enough approach to
the Commonwealth to bring afternoon and evening favored showers
and thunderstorms towards the end of the week.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Late evening update.
At least for now, winds have died down faster and CIGS
trended up faster, than I expected. TAFS adjusted for
these parameters.
Earlier discussion below.
Main change for the 00Z TAF package was to hold onto the
clouds longer overnight into Sunday, given the deep low
over the northeast states and near record cold air being
advected into the area.
Likewise, expect winds to stay up for most part into
Sunday, given the above factors.
CIGS will range from MVFR and IFR over the mountains,
to VFR further to the southeast.
Outlook...
Monday-Wednesday...Mainly clear with VFR conditions.
Thursday...Chance of showers north and west, hot and humid SE.
&&
.CLIMATE...
May 2025 Precipitation Rankings
Site May 1-30, 2025 | Wettest May on Record
-----------------------------------------------------------
Harrisburg 9.72" Wettest | 9.71" in 1989 (previous)
Williamsport 6.99" 5th wettest | 9.91" in 1919
Altoona 7.24" 3rd wettest | 7.31" in 1960
State College 6.47" 9th wettest | 9.45" in 1894 (~5/29)
Record precipitation was observed in Harrisburg on May 30th
when 1.75 inches of precipitation occurred. This broke the
previous record of 1.39 inches set back in 1953. For reference,
a continuous weather record has been kept in Harrisburg since
1888.
Record precipitation was also observed at Johnstown, where 1.05
inches of precipitation occurred, breaking the old record of
0.89 inches set back in 1975.
A seasonably strong/deep area of low pressure (~990mb) is
forecast to move across southeastern Pennsylvania overnight. The
record low pressure for May at Harrisburg is 983.4mb.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Bowen
NEAR TERM...Dangelo/Bowen
SHORT TERM...Dangelo/Bowen
LONG TERM...Jurewicz/Martin
AVIATION...Martin
CLIMATE...Steinbugl/NPB
NWS CTP Office Area Forecast Discussion
